Inductor Core with Graded Resin Content for Crack Suppression
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Solution Overview
Problem
Existing inductor elements with magnetic powder and resin cores tend to form cracks and have low inductance due to poor bonding interfaces and low magnetic material density, especially when trying to increase inductance by reducing resin content.
Innovation Solution
The inductor element design includes a core with varying resin content across different parts, where the outer circumference part has a higher resin content than the top and bottom board parts, and the center part has a lower resin content, enhancing adhesiveness and inductance while maintaining high magnetic material density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the resin component is reduced to increase the ratio of magnetic powder, then the density of the core increases and inductance improves, but the molding property deteriorates and cracks easily form
Solution Approach 1:
The patent applies local quality by creating non-uniform resin distribution within the core, with higher resin content at bonding interfaces (outer circumference parts) and lower resin content in the center. This localized variation in resin content allows the bonding interfaces to have improved molding properties and crack resistance, while the center maintains high magnetic powder density for optimal inductance performance.
2Reliability
If the resin content is increased to improve molding property and prevent cracks, then crack formation is suppressed, but the density of magnetic material decreases and inductance is reduced
Solution Approach 1:
The patent implements local quality by strategically placing higher resin content at the outer circumference parts (bonding interfaces) where crack resistance is needed, while maintaining lower resin content in the center part to preserve magnetic material density. This spatial differentiation allows each region to have the resin content optimized for its specific functional requirement.
3Ease of manufacture
If green compacts are re-pressurized to form the inductor element, then the coil component is obtained, but cracks easily form at the bonding interface between green compacts and along the end face of the coil part
Solution Approach 1:
The patent applies preliminary action by pre-distributing resin-rich regions at the bonding interfaces before the final re-pressurization molding process. This preliminary resin distribution ensures that when green compacts are re-pressurized and bonded, the interfaces already have sufficient resin content to prevent crack formation, thereby improving bonding interface strength without compromising the molding process.
Data Source
AI summary
The present invention is an inductor element having a conductor wound in a coil form, and a core part surrounding the coil and including a magnetic powder and a resin. The core part includes a top board part and a bottom board part respectively covering both ends of the coil, and an outer circumference part positioned at an outer circumference side of the coil, and a resin content of the outer circumference part is larger than a resin content of the top board part and also larger than a resin content of the bottom board part.